Identification circuit for automatic or semiautomatic telephone systems



Allg- 17, 1954 M. DEN-HERTOG IDENTIFICATION CIRCUIT FOR AUTOMATIC ORSEMIAUTOMATIC TELEPHCNE SYSTEMS Filed NOV. 25, 1950 7 Sheets-Sheet l y"3 .N lmflia 4 wk u2 IN VENTOR MART/NUS DEN HERTOQ BY ATTORNEY Aug. 17,1954 M. DEN HERToG 2,686,840 IDENTIFICATION CIRCUIT FOR AUTOMATIC v ORSEMIAUTOMATIC TELEPHONE SYSTEMS Filed Nov. 25. 195o 7 Sheets-Sheet 2INVENTOR MART/N05 DEN 44E/Woe ATTORNEY Aug. 17, 1954 M. DEN HERTOG2,686,840 IDENTIFICATION CIRCUIT FCR AUTOMATIC 0R sEMIAUToMATICTELEPHONE SYSTEMS Filed Nov. 25, 195o 7 sheets-sheet s REG.

asl/ll INVENTOR nner/Nus as Heeroa ATTORNEY Aug. 17, 1954 M. DEN HERTQG2,686,840 IDENTIFICATION CIRCUIT FOR AUTOMATIC OR SEMIAUTOMATICTELEPHONE SYSTEMS Filed Ncv. 25. 195o 7 Sheets-Sheet 4 INVENTCR MART/NUSDEN HERTOG `ATTORNEY 2 c mm ms G E oww TFDH. RT E Emu HMT .invV mon .umm.Hm MMA II uw TS mm I 4 5 40. l 7.. 1 .A

7 Sheets-Sheet 5 Filed Nov. 25. 1950 INVENTOR 3m num. .vw

MART/Nus 05N 11e/woe Y Y e? a@ so ATTORNEY Aug. 17, 1954 M. DEN HERTOG2,686,840 IDENTIFICATION CIRCUIT FOR AUTOMATIC OR SEMIAUTOMATICTELEPHONE SYSTEMS Filed Nov. 25, 1950 7 Sheets-Sheet 6 FN/ ,4,4 INVENTOR0c MART/Nus DEN HERToa Q ATTORNEY f Aug- 17, 1954 M. DEN HERTOG2,686,840*

IDENTIFICATION CIRCUIT FOR AUTOMATIC oR sEMIAuToMATIc TELEPHONE SYSTEMSATTCRNEY Patented Aug. 17, 1954 IDENTIFICATION CIRC 0R SEMIAUTOMATI'ITEMS UIT FOR AUTOMATIC C TELEPHONE SYS- Martinus den Hertog, Antwerp,Belgium, assigner to International Standard ElectricCorporation, NewYork, N. Y.`, a corporation of Delaware Application November 25, 1950,Serial No. 197,623 18 Claims. (Cl. 17918) The present invention relatesto an automatic or semi-automatic telephone system or similar alreadybeen applied in practlce but in the. known arrangements use was made ofalternating current potentials in which `separate direct currentcircuits were utilized for putting. the identification into operation.

The object of thel invention is to provide an improvement of thesewell-known circuit arh rangements in which a reliable operation is atftained with a simplified equipment.`

In accordance with the invention the said potential is a single directcurrent potential'` of predetermined value, which in series with` aresist- In accordance with the circuit arrangement described in the saidpatent itisr however; neces` sary to allot a potential oi"4 differentvalueto each may alsooperate a starting circuit by closing a circuit viaa rectiiier, the potential on the conductor being higher than thatconnected in the starting circuit to said rectier, which startingcircuit thereupon hunts for and seizes an idle of said com-monidentification circuits and maintains the circuit responsive during thetime that it huntsl forthe marked conductor of the calling line.

group ofidenticationfinders is provided. in common and wherein. aselector, associated with the identification circuitsy selects andseizes a free identification nder inl that group, to which the tion`circuitto the Wanted group. This potential is supplied; thereto throughthe corresponding starting. circuit which has seized the identicationcircuit.

After the hunting ofthe conductor by the identication circuit, a circuitmay be closed from the latter to said conductor via the Winding of arelay to ground, whereby on the one hand the the starting circuit ceasesto function, because the poten-tial on the conductor is reduced to avalue at which the rectiiier is no longer conductive', and on theA otherhand said relay operates andholds the identicationcircuit under thecontrol! of the direct current potential.

In the alcove mentioned patent, the resistance provided in some of thecircuits, from which identiiicationis requestedfserves solely as aprotecting resistance and not for creating a lowered scribed: in thepreceding paragraph. In the aborennentioned patent the. reduction ofpotential is not utilized to make the starting circuit inoperative.. butaccording to said patent; the

lnl accordance with a further feature of this. invention, after theidentification circuit has hunted for a conductor, a physical circuit isthen established o-ver saidl conductor between this identificationcircuit and the point from which the identification is requested. Thisphysical circuit may be used for setting a by-path under the control ofthe identification circuit, if necessary, via a plurality of conductorsfrom the identification circuit to said point. Via said conductor andfrom the identification circuit, a characteristic potential for thiscircuit is connected to the circuit requesting the identification, whichpotential characterises the last mentioned circuit for setting theby-path.

In accordance with the invention a finder switch may be inserted in thisby-path, this switch either being associated with each identificationcircuit or with each of said points from which identification can berequested, wherein the by-path is set by extending the physical circuitvia a wiper and arc Contact of said finder back to the identificationcircuit under consideration at the moment the finder reaches the wantedposition under the control of the identification circuit.

This invention differs further from that disclosed in theabove-mentioned patent in that in this application the physical circuitis admittedly used for setting,r a by-path, but this is not effectedunder the control of the common identification circuit but ratherindividually for each f the circuits from which identification can berequested, and that consequently the physical circuit is not extended.through this last mentioned circuit to a common identification circuit.

After the .by-path has been established the physical circuit between theidentification circuit and the identification conductor of the callingline may be opened and a circuit for holding the identification circuitmay be established directly from the circuit from which theidentification is requested to the identification circuit, via one ofthe conductors of said by-path.

The finder may be associated with each identification circuit in whichthe position of this iinder gives an indication to the identificationcircuit about the nature of the point from which the identification hasbeen requested.

rlihe nature of the point from which identifica-i tion has beenrequested may, according to the invention, furthermore tication circuit,via one or more wipers of the said finder switch, from this point aftersetting the by-path.

According to the nature of the point from which identification isrequested, the number of the calling line may be signalled over theby-path in different ways, e. g. for local calls by means of directcurrent impulses and for distant calls by means of voice frequencyimpulses.

Depending on the nature of the point from which identification isrequested, the number of i `ansrnitted digits may be different, e. g.for calls in the local network, the digits of the subscribers numberonly, and for calls to other networks these same digits preceded by thedigital prefixes of this network.

Finally, between the originating exchange and the point from which theidentification is requested, one or more junctions may be inserted inthe built up connection, this identification being started becausethe-marking potential is applied to one of the conductors of theincoming end of the junction circuit and makes an identification circuitoperative, which, via another junction, establishes a by-path to theprebe signaled to the idenf ILO `ceding exchange in the connection overwhich by-path the number of the calling line is transmitted from theoriginating exchange in the form of voice frequency impulses.

In accordance with the invention, the switch associated with saididentification circuit which hunts for the point from which theidentification is requested may operate the identification circuit in adifferent manner, according to the nature of the point, e. g. becausethe voice frequency impulses are converted into direct current impulses,if the identification is requested locally, voice frequency impulses aretransmitted unaltered via a subsequent by-path.

The invention'will be described with reference to the accompanyingdrawings which schematically show this invention while omitting thoseparts of the system which are not essential for a good understanding ofthe invention.

Fig. 1 shows a junction diagram of an exchange in which identificationin accordance with the invention is applied.

Fig. 2 shows the junction diagram of the second exchange connected withthe exchange of Fig. 1 via two groups of junctions, one for the trafficin each direction.

Fig. 3 is the junction diagram of a third exchange which in turn is`connected by two groups of junctions to the exchange of Fig. 2.

Figs. 4, 5, 6 and '7, which should be read in combination, as shown inFig. 8, schematically show simplied circuits related to an embodiment ofthe invention.

In more detail, Fig. 4 represents a master false call circuit from whichidentification can be requested, together with a cord circuit for aconnection with which said master false call circuit has becomeassociated, as Well as a starting circuit permanently associated withline finder circuits.

Fig. 5 schematically represents an identification common circuit whichcan be seized by the starting circuit.

Fig. 6 schematically represents an identification finder circuit whichcan be selected from the identification common circuit.

Fig. '7 schematically represents a finder which is used for setting aby-path to the circuit which requests an identication and which is alsoused for other purposes which will become apparent from the description.

The various operations and advantages of the system will be describedseparately.

Identification of the calling line by a direct cur- Tent potential onthe metering wire In Fig. 1 a. local connection, e. g. between thesubscribers A and B is built up via the first and second lineiinders LLFand ILLF, the group selectors LGS, ILGS and IILGS and a final selectorFS.

The circuit with which ILLF and LGS are associated will be called thecord circuit.

A call to a local operator, e. g. for rapid traffic, is, according toFig. 1, established via ILF, LLF, the rst group selector LGS and aspecial service selector DGS, to a junction for rapid trafiic CLRJ Aconnection to a distant exchange, e. g. to

subscriber D thereof (Fig. 2) is established from subscriber A (Fig. l)via I LF, ILLF, LGS, the outgoing end OGJi of a junction circuit and viathe two-wire junction to the distant exchange (Fig. 2) and subsequentlyvia the incoming end.

of the junction circuit, the incoming group seor, in case of tandemconnection, these lector INCGS and the selectors III.GS and FS' to thesubscribers line. D.

For the sake of completeness, Figs.1 and 2 also show the members viawhich a subscriber C of the exchange (Fig. 2) may build up a connectionto a'subscriber B of the exchange (Fig. 1), for which separate junctioncircuits forthe trail-lc in this direction have been provided betweensaid exchanges.

-By combining Figs. 1, 2 and 3, one above the other, it also becomesclear how a connection may be built up via more than one junction intandem, e. g. from subscriber A in Fig. l to subscriber F in Fig. 3 viathe exchange of Fig. 2 viz. via I.LF (Fig. 1), II.LF, IGS, OGJi,junction from Fig. l to Fig. 2, INCGS (Fig. 2) OGJz, junction from Fig.2 to Fig. 3, INC.GS (Fig. 3) IIIGS, FS", to subscribers line F.Reversely a connection may be obtained from subscriber E in Fig. 3 tosubscriber B in Fig. 1 via the exchange of Fig. 2, via I.LF" (Fig. 3),ILLF", I GS, OGJi, junction from Fig. 3 to Fig. 2, INCGS (Fig. 2), OGJz,junction from Fig. 2 to Fig. 1, INCGS, III.GS and FS to subscribers lineB.

By way of example it is shown in Fig. 1 how in case of a false call frome. g. the line A the later is switched through a common false callcircuit MFC, viz. via II.LF and the nders FF and MF which for thispurpose are connected up to the cord circuit seized by the false call.

Indentiilcation of e. g. the calling line A in Fig. 1 may take place inthe following cases:

i (a) In case of a false call wherein identication may be requested bythe common main false call circuit MFC and the number of the callingline will then appear on a number indicator NIi associated with MFC.

(b) In case of a` call to a rapid call junction CLRJ wherein the requestfor identification is eiected by pressing a key IK by the rapid tolloperator and then the calling number will appear on a number indicatorNI2 associated with the operators position. l

(c) In case of a malicious call to another subscribers line, e. g. B inFig. 1. For this purpose the subscribers line equipment at the exchangeof line B is provided with a special matching equipment MC with the aidof which, in case of a malicious call, the subscriber B may initiate theidentication of the caller, the number thereof appears on a numberindicator N13 provided at an operators position.

(d) In case the calling subscribers line is provided with a device forprinting the calling subscribers number upon absence or with a devicefor indicating the calling subscribers number when answering. In bothcases the called subscribers line at the exchange is equipped with Y anadditional matching equipment (MC) from which the identication isinitiated and which causesthe calling number to be transmitted via thesubscribers line to the equipment at the subscribers station, e. g. thenumber indicator NIi. In both cases c and d the identification isrequested from a control circuit FIM common to the various subscribersline equipments.

(e) In case the identification is requested from an exchange which viaone or more junctions in tandem is connected with the exchange to whichthe calling subscriber is connected, the identification is requestedfrom a selector circuit FSi, e. g. (Fig. l), with the aid of which fromthe distant exchange a by-path via another junction is established tothe outgoing end of the junction which was used for building-up theconnection..

(f) Other cases in which identifications may be requested have not beenshown on the drawings and e. g. relate to identifying calls forautomatically printing metering tickets with automatic toll calls inwhich case the identification is requested from the toll equipment.

In all above-mentioned cases on behalf of identincation use is made of aconductor which from the line equipment of the calling line isgalvanically connected through finder and selector stages totheequ1pment from which the identification is requested. To this end, inthe described embodiment the so-called metering wire, that is to say theconductor in the subscribers line circuit, with which a service meter isconnected, is used. For the sake of clearness this wire is indicated bya separate thicker line in Fig. 1 and in case of a local call, it isgalvanically connected through the line iinder circuit, the cord circuitand all local group selector stages to the final selector stage.Furthermore for distance calls this wire is galvanically connected tothe outgoing end of distant (two wire) junctions from which a physicalconnection may be obtained to the selector FSi vserving for setting aby-path for identification between distant exchanges. In case of falsecalls the metering wire, via the lnder circuit FFfor false calls ormalicious calls and a finder MF, is connected to a main malicious callcircuit MFC if these circuits are connected with a cord circuit. Fromthe inal selector circuit the metering wire (either directly via a wiperof the iinal selector if the latter is available, or otherwiseindirectly via a by-path which is provided by specially providedcircuits for this purpose) may be connected through to the equipment ofa called line which said equipment is indicated by MC in Fig. l. rIhespecial by-path circuits in question have been shown in Fig. l by thecontrol circuit FIM comprising the nders PF and PS with the nder circuitFIF.

It follows from the above statement, that the metering wire may leadgalvanically to all circuits, from which identification may be requestedat the same exchange to which the calling subscriber is connected-up.

In case of connections which are built-up via an incoming circuit forjunctions, the conductor which in the selector stages to be mentionedhereinafter for identiiication, terminates into this incoming circuit ona conductor which as regards identification performs the same functionsas described above for the metering wire and which in an analogousmanner is called metering wire, though in this case no metering can takeplace via this conductor.

In accordance with the described embodiment the metering wire is usedfor identifying the number of a calling subscriber and for this purposethe said conductor is individually connected for each subscriber in thesubscribers line circuit, viz. in the terminal arc of one or morespecially allotted identification iinders IF, provided in common, e. g.per two groups of each one hundred subscribers. The finder switches inquestion therefore include the metering wires exclusively as part of thesubscribers circuits.

In the incoming circuit of junctions the so called metering wire is alsoconnected in the terminal arc of one or more specially allottedidentification nnders IF2 (Fig. 2) which is or are provided for eachgroup of junctions, incoming from a same distant exchange, or, in casethis 5 number equals e. g. more than 100 for one or more groups (whichamount corresponds with the number of outlets of IFz) for each sub-groupof 100 lines or less.

In the line iinder circuit LLF, the metering Wire, via a small rectifierR1, is connected to a common point to which all line finders, each ofwhich in the described embodiment serve two groups of hundred lines, areconnected, wherein this point is further connected to an identificationstarting circuit SC, which is also provided per two hundred lines. Thearrangement is such that each ci the starting circuits belongs to agroup or finders IF, serving the same two hundred lines.

In the incoming circuit for junctions (Fig. 2), thel so called meteringwire is also connected via a rectifier (Rr) to a common point to whichall circuits of a group or sub-group are connected, wherein this pointis further connected to an identincaticn starting circuit SC', beingalso provided per group or sub-group, and wherein the arrangement issuch, that each of these starting circuits belongs to a group of ndersIFz serving the same group or sub-group of incoming junctions irom asaine distant exchange.

It is assumed that the operation of the service meter SM taires place byconnecting a negative potential of i8 volts Via 250 ohms to the meteringwire.

Identification in case of a local call A short general description ofthe identification operations in the case of a local call will nrst ofall be given in relation to Fig. i.

Assuming for example that a false call occurs, for instance when theline conductors leading to subscriber A are permanently bridged, theregister will eventually detect this false call and will cause a masterfalse call circuit MFC to become attached to the cord circuit viafinders MF and FF, whereby the .false call can be signalled to saidfalse master call circuit MFC. The above is well known and need not bedescribed further, the invention being primarily related to thoseoperations which start as soon as a circuit, e. g. MFC, requests anidentification.

. For such a purpose, the main false call circuit MFC will connect asmall positive potential indi-cated by v. on Fig. 1 to a conductorindicated by a thick line and leading to the cord circuit. Theconnection of this small positive potential to the cord circuit iseffected by means not shown but which may consist of an operators key orrelay contacts in the main false call circuit MFC.

This positive potential of +15 v. is applied via a resistance (notshown) and accordingly a reduced positive potential will appear atrectifier Ri, this being due to the potentiometer eiiect produced by thesubscribers meter SM. This reduced positive potential is not sufficientto cause `the operation of the subscribers meter SM, but

will be sufficient to operate the starting circuit SC. The startingcircuit SC will now hunt by .cans of the finder CC for a freeidentification common circuit ICC. Upon said identification commoncircuit becoming attached to the starting circuit SC, the latter willnow transmit some digital information concerning the number of thecalling subscriber` A. This can be done due to the fact that thestarting circuit SC is provided in common for a predetermined group ofsubscribers lines and will be obtained in co-operation with a nder DSwhich is associated with the identification common circuit ICC. Saidtransferring of preliminary digital information f this will be performedwith the help to the identification common circuit ICC' will become moreapparent from the detailed description.

Finder BS which is also attached to the identincation common circuit ICCwill now be made to hunt for an identiiioation iinder IF which servesthe-same group of lines as that served by the starting circuit SC.

TJpon said identiiication finder IF having been seized, it will be madeto hunt under the control of the identincation common circuitICC forsaid reduced positive potential which is present on the metering wireindicated by a thick line on Fig. 1.

All the subscribers metering wires in the group served by the startingcircuit SC and by the identification nder IF are connected in one .ormore banks of the identication under IF. this manner, when the finder IFhas found Said reduced positive potential on the metering wire ofsubscriber A, its position will be characteristic for the callingsubscriber A. Accordingly, additional digital. information can now besent into the identiiication common circuit ICC. Again, of iinder DS ina manner which will become more apparent from the detailed description.

The finder DS having now performed its auxiliary functions in connectionwith the determination of the calling subscribers number for theidentification `common circuit ICC, it will now be made to hunt, underthe control of the identicatlon common circuit ICC, for ley-pathconductors leading to the circuit which requested the identification, i.e. MFC.

It may be remarked that as soon as the identiiication finder IF is inits through condition, the common identiiication circuit ICC will causethe positive potential at the metering wire to be decreased in such amanner that it will no longer be suiiicient to maintain the startingcircuit :SC in its actuated condition whereby the latter will bereleased and made available for other identincations. At the saine time,the identification common circuit ICC will now be held via theidentification finder IF and finder BS. Further, as soon as the completedigital information has been stored in the identification common circuitICC, the latter will temporarily apply ground potential to the meteringwire causing switching operations at the master false call circuit MFCwhereby it will now be possible to set nder DS on by-path conductorsdirectly leading to the master ialse call circuit MFC, the latterdirectly holding the identification common circuit ICC v ia finder DS.In these conditions, identication finder IF and finder BS can now bereleased.

The circuit which requested the identification, i. e. master false callcircuit MFC will now signal to the identification common circuit ICCthat'this is the case of a local identication and accordingly, theidentification common circuit ICC will now send D, C. impulsescharacterizing the calling subscribers number on the number indicatorN11 located in the master false call circuit MFC. Upon said numbei1being obtained on the number indicator N11 the key can now be releasedWhereby finder DS will 'be released and the identication common circuitICC will be brought back to its normal condition.

The above operations will become more apparent in relation to Figs. 4 to7 which representi'n detail parts of the circuits shown in Fig. 1 andwhich have been referred to above.

A detailed description will now be given in connection with Figs. 4, 5,6 and 7 of the `manner in which a line can be identified from a masterfalse call circuit MFC.

Assuming that the operated over The energization of relay Dr will causerelay Er to be operated over make contact D2. Both relays are providedwith a holding circuit including respectively makecontact D1 and makecontact E1. switching over of the the source of positive potential +Vbeing applied to the cord circuitof the connection via resistor r3, makecontact D3, circuit of the finder MF which has become attached to thecord circuit and from there via the circuit of second line finder IILF,circuit of rst line nder ILF, metering wire and subscribers meter SM toground. All the above mentioned finders can be assumed to be in theirthrough condition, this having been performed in the usual manner, whichhas no bearingupon the present invention, by means of additionalcircuitry and brushes (not shown). A through-circuit being nowestablished from the source of positive potential +V to ground, apositive potential will circuit ILF which Sii and E5.

is sufficient to make rectifier R1 conductive whereby this positivepotential will a static switchSSi of the kind to actuate application ofL. Cabes, Serial No. `765,022, led July 31, 1947. This static switch SSiis such that when a positive potential is applied via rectier R1, and ifsuch potential is above The positive potential will however not besufficient for the operation of the subscribers meter SM. The relay A1-will release if the voltage falls below this threshold value.

The static switch SE1 is located in an identification starting circuitSC, which is provided in common for a group of 200 lines.

As soon as relay Ar is attracted, it will close an operating circuit forthe power magnet CCM via break contact T1, make contact A2 and breakcontact B2. This power magnet CCM controls a finder CC' which isprovided for each identication starting circuit SC and which will nowhunt for a free identification common circuit ICC. A free identicationcommon circuit ICC is characterized by having a test potential providedfrom negative battery via the winding of relay C'lr, break contact Ads,brush SSa of a step-bystep switch SS pertaining to each identificationcommon circuit ICC, olf-normal contacts BSON1 andDSON1 of finders BS andDS also attached to circuit ICC, to a contact in the d bank of inder`CC. Upon the brush CCd meeting this test potential, test relay Tr (SC)will be energized via make contact Ai, by means of its high resistancewinding. The usual double test relay SR is also provided, said relayhaving a low resistance winding and becoming energized via make contactT1 if there is no double test. In well known manner, the energization oftest relay T'r will interrupt the operating circuit for the power magnetCCM at make contact T1 whereby the nder CC will stop on a freeidentification common circuit ICC. Simultaneously with relay Sr, relayClr (ICC) will be energized and via make contact C11, break contact Sdi;and make contact Aa and S4, an ope ating circuit will be prepared forrelay Adr. i

Since the identification starting circuit, SC

key K will also result in` now appear in the line rlnder` `will beperformed by bridging terminals such as Pairs ci Operated 10U-Ime groupstlglgags relays in connected ICG A3, brush CCe, conductor e1, breakContact Sdg and make contacts relay Br will close Cli and Aa2 ingprovided for relays Abr and Aer, if these are also energized. Therelease of relay Clr will not, however, cause `the de-energization ofrelay Adr since a holding circuit is -provided for the latter via makevcontact Adi, break contacts I-Ilz Ppi, Hmi, Pq1, and Side. Also, therelease of relay Tr will not restart the power magnet CCM since theoperating circuit for the latter is now interrupted at make contact B2The releaseof relay Tr will permit relay Cr to be energized over makecontacts B3 and A2 and break contact T1.

Relay Si now being released, and relay Aar (and/or Abr, Aer) being heldover make contacts Adi and Aci (and/or Abi, Aci), conductors a1 and c1leading from the identification common circuit ICC to the identificationstarting circuit SC are free to be used for sending additionalinformation to the identication common circuit ICC. Via make contact C1of relay Cr (SC), an alternating current potential having a phase whichis characte-ristic of the G-line group to which the identicationstarting circuit SC belongs and which is schematically indicated by qBawill be applied to conductor ai and via make contact Ad'z and breakcontacts Sds, Hai, will reach the alternating current comparator ACClocated in the identification common circuit ICC.

This alternating current comparator is of well known design and has, forinstance, been described in the application of L. Cabes, Serial No.

amplitude but between which there is a difier- If this phase differencereaches the alternating ence of phase. a predetermined value, e. g.,zero, current comparator reacts.

At the same time that the alternating current signal is applied to themarking side of the alterhating current comparator ACC, the nder DS willbe started, its power magnet DSM being energized over the followingcircuit: break contacts Zmi, Sar of relays Zmr and Sar, make contact Adeand break contacts G51, Oti and Eti.

The 'First ten contacts in the e bank of the finder DS are eachseparately connected to an alternating current source, i. e., (pm w,each having a characteristic phase and each of said characteristicphases corresponding to a thousands digit. Accordingly, when the brushesof switch DS and more particularly the brush DSe reach the contact towhich an alternating current voltage, e. g. qba is connected and bearingsaid predetermined phase relationship, e. g. same phase,

tcy the alternating current voltage which has been connected to thecomparator ACC from the starting circuit SC, the comparator ACCwill-react, since the alternating current potential found via brush D'Secan reach the comparator via break contact Has.

The operation of the comparator ACC will cause the immediate buttemporary energization of relay G51', said energization interrupting theoperating circuit for the power magnet DSM at make contact Gsi. Itshould be understood that this temporary energization oi relay Gsr is tobe obtained by additional circuitry, not shown, by means well known tothose skilled in the art. The temporary energization of relay Gsr willthen cause the step-by-step switch SS to make one step, this beingschematically indicated on the ngure by the connection of an earth tothe step magnet SSM via make contact G52. Before the step-by-step switchSS has time to move to its second position, relay Har will be energizedover make contact G54, brush SSa in its first position, make ContactGsa, and break contact Sda. Via make contact Hai, auxiliary relay Sarwill then be operated.

By the time step-by-step switch SS has moved to its second position, thenumber of the thousands digit will have been registered in theidentification common circuit ICC by means of the three brushes DSa, DSDand DSc of the finder DS. These brushes are now resting upon a set ofcontacts in a position which is characteristic of the thousands digit.By means of suitable connections in the (1, b, c contact banks oi thender DS, it is now pcsisble to register the thousands digit by usingcode relays. Theseconnections have been diagrammatically indicated byJFi while the registering unit for the thousands digit has beendiagrammatically indicated by Bar-Bdfn In well known manner, thisregistering unit comprises a set of four relays (not shown) which can beenergized in various combinations so that they will store the thousandsdigit on a binary basis, e. g., the well known 1-2-4-6 binary code. Thestoring of the information of the registering unit Bar--Bdr will beperformed when the alternating current comparator ACC reacts therebyoperating temporarily relay Gsr, the latter then applying ground to thebrushes DSU., DSD, DSC via conductors a2, b2, c2 and make contacts Gss,Gse,

identification finder 12 G57. Since relay G51' is only temporarilyattracted, holding means (not shown) will be provided in well knownmanner for the four code relays (not shown) which form the essentialpart or" the registering unit Bur- Bain It is to be noted that when thestep-by-step switch SS has reached the second position, relay G31' hasalready released and accordingly relay Sbr cannot then be energized. Onthe other hand, the release of relay Gsr will not affect the operatedrelay Har since the latter' is maintained in its attracted position viamake contacts Haz and Ads.

As soon as relay Gsr has released and since relays Har and Sar are nowenergized, an operating circuit is now closed for the power magnet BSMof the iinder BS, over the following circuit: break contact Sbs, makecontacts Sci and Ads, and break contacts Gsi, Oti, Etr, whereby finderBS will start hunting for an identication finder It is to be noted thatwhen relay Cr in the starting circuit SC energizes, it connects brushCCc of finder CC to multiple point Q via make contact C3. This multiplepoint Q leads to all the identiiication finder circuits which serve thesame group of 200 lines as that which is served by the identicationstarting circuit SC.

Since relay Har is operated as soon as the alternating currentcomparator ACC reacts for the i'lrst time, a loop circuit for analternating current voltage cx having a phase which is characteristicfor each identification common circuit ICC is closed Via the followingcircuit: break contact Sov, make contacts i-lc and Ada, conductor c1,brush CC of iinder CC, make contact C3, multiple point Q, break contactATG of relay Arr in the identication nder circuit, of finder BS, breakcontact Scio, make contact Hag to the testing side of the alternatingcurrent comparator ACC, marking side oi the comparator ACC, make contactHai and break contact Sca, it being understood that this loop circuit iscompleted when the brushes of finder BS reach an circuit to which thealternating current voltage having a characteristic phase cx is appliedvia multiple point Q. When such an identication iinder circuit isreached, the alternating current comparator ACC, which in thisparticular embodiment has been designed to react when the difference inphase between the marking and the test voltages is equal to zero, willbe actuated for the second time, thereby causing a second energizationof relay Gsr. The operation of the latter relay will cause theinterruption of the circuit for the power magnet BSM, at make contactG81, and accordingly the finder BS will be made to stop on a suitableidentiiication iinder circuit.

Remembering that the step-by-step switch SS is now on its secondposition, the new and temporary energization of relay G31' will nowcause the operation of relay Sbr Via make contact G54 and brush SSei.When relay Sbr operates, a holding circuit for said relay is preparedvia make contact Shi, winding or Ser, make contacts Has and Ads, andwhen step-by-step switch SS moves to the third position as a result ofthe temporary energization of relay Gs (make contact Gsz), relay Scrbeing no longer short-circuited to ground at make contact G54, will beenergized.

As soon as relay S197* energizes, relay Arr in the identification findercircuit is energized over break contact Brz, brush BSU., conductor a3,make y 14 Contact Sbs andbreak ContaCt Sd4. The Snergiand Ser` alsorelease (break contacts Hai and t"lation f relay Arr will now completeanoperat- Haz). The ground which is supplied to conducing circuit for thepower magnet IFM Of the tor e3 and brush BEe for the operation of relaysidentication iinder IF via the following circuit: Arr and Brr will nowbe provided over make make contact AT5, break contact Brs, brush BSc, 5contact Sd?. Relay Otr (or Etf) will release CODdLlCtOr C2, make COHaCSSTJB, SL14, Ads and but if relay Otr has been energized (odd D-linebreak contacts G'si, Oti, Eti. i group) relay Oer will be attracted overmake con- The ldelltloalwninder IF Will 110W be mad@ tact Ota and thenheld over make contacts Oei to hunt for the subscribers line in theparticular and Ada G-lille grQUD SerVed b y by the ndel 1F', Whose 10 Itshould be remarked that as soon as the ideneach group of identificationnders serves a 200- l5 or make Contact Ars te brush BSC or brush BSBd,line group, two brushes, e. IFc and IFe are used and then via make orbreak Contact 0,63, make for testing for the presence of positivepotential Contact 3de and break Contacts Syl and Saa Whn one 0f thebrushes eg- IFCgOf the iden" 20 rent potential which was present atrectier R1 common circuit ICC over brush IFc, make conrelease te ethe atact Ari, break contact Bm, brush BSb, conductor Relay Adr ind leglnlcoob3 make Contact Sm and break Contact sdm' ICC which was previouslymaintained over make This static switch SSS is identical to that whichAcontact Adly break contacts H12 ppl Hml Pq1 1s used inthe startingcircuit SC,i..e.SS.1. Upon and make contact Sdg, after having previouslySad DOS/TUV@ potentlal 0n the'metermg Wn'e bemg been held over conductore1 will now be held found the Static Switch S53 Wm react Causing 30directly to ground in the identification common the enelgzaton 0f relayO Since Contact SC3 circuit ICC via make contact Adi break contact isclosed, relay Scr beingoperated. In the par- H12 and make Contact pplRelay Pm. Operates ticular embodiment described, it has been asrelay PerIsilleolhagrthoglrrgnv Ocorlgflggg The starting circuit SC having nowbeen reg p. e t d leased, it becomes available for other calls alsoidentification finder IF, while the metering wires for the even 10o-linegroups are connected in the s crib 818 1i "e bank of the identicationnder IF. In the latter case, the circuit goes over brush IFe, make monstartlpg clrcmt' Also 1t Wm be npted that contact Ara, brush BSd,`conductor da, make con- 40 tact Sm to the static switch S52, similar tothe trol of the master false call circuit MFC. In this static switchesreferred to above, whereby relay Etr would be energized when therequired positrol of cumuli; MFC tive potential is met on the meteringwire.

As soon as one of the static switches SSz or SSa is reacts, theidenticationnder IF will be made to stop on the required set ofterminals. Also, when relay Gsr was operated for the second: time(during search for a suitable identiication finder), it causedstep-by-step switch SS in the identication common circuit IC to make asec- .y ond step by means of make contact Gsz whereby hnseigebgemg' thebrushes of said step-by-step switch SS were en 1 c moved to the thirdposition.

In this position, relay Sdr is nowenergized over brush SSa in the thirdposition and either of make contacts Otz or Etz. `As soon as relay i tothe ldentlctal. Sdr operates, it locks over `make contacts Sdi and Ada.i

Since the energization of either relay Otr or relay Etr interrupts thecircuit for the power Aar, Abr, Aer have been 'energized in a comtainsthe hundreds digit, i. e. odd or even 100- Which was supplied viaconductor aa and brush une group in a ZOOIme group there remains BSa torelay Arr. 'Ifhe latter was, however, pro"` only to obtain the tens andunits digits. vided with a holding circuit over make contact F01' thisPLIIDOSG, Various alternating Current Arv, Winding of relay Brr, brushBse and make potentials have been connected to the contacts in contactSbs. Accordingly, when the ground is the a and b banks of theidentincation nder interrupted on conductor aa, relay Brris nolonger IF.Each Contact in the a bank is connected short-circuited and operates inseries with the to a particular alternating current potetnial alreadyoperated relay Arr. j which has a phase characterizing the tens digit,It is to be noted that upon theenergization of while each contact in thebank is connected relay Sdr relay Har` is `made to release (make to analternating current potential having a contact SdB), and accordinglyrelaysfSar, Sor 7 phase which is characterized for the units digit.

These have been respectively indicated by 41m,- and am.

Since relays Ctr or ,Etf are only temporarily energized, and since relayHar has been released, an operating circuit is again closed -for thepower magnet DSM or the finder DS which vvill now start a second huntingmovement. Before the finder DS starts to hunt again, the alternatingcurrent potential, i. e. pcb having a phase characterising the tensdigit Will be connected to the alternating current comparator ACC(marking side) via brush illu, make contact Bz, brush BSc, conductor as,break contacts See and Sfi, make contact Sda and break contact Hui. Thischaracteristic alternating current potential should of course differirom the alternating current potentials B1 10 which were used for thethousands digit, since otherwise beiore the finder DS starts to huntagain, it might stop in the first field of bank contacts which was usedtor the determination of the thousands digit. As soon as the brush DSeof under DS reaches a contact to which an alternating current voltage(ecru) is connected and which corresponds to the alternating currentvoltage (41GB) marked on the com arator ACC, the latter will react forthe tb test alternating current potential reaching the comparator ACC.via brush DSe and break contact Hug., Accordingly, relay G31' will beenergized for the third time and will cause the finder .DS to stop andthe step-by-step switch SS to be moved to its fourth position, i. e. bymeans oi make Contact G52. Before the step-bystep switch SS has time tomove to its iourth position, the temporary energization of relay GSTWill apply ground to brushes DSa, DSb and DSC, respectively, via makecontacts Ges, Gss and Gsfz. Since these brushes are now resting in aposition chracteristic for a particular tens digit, itis possible bymeans of suitable connections to the bank contacts (diagrammaticallyindicated by da) to store the tens digit into a second registering unitdiagrammatically indicated by Car-Cdr. rThis second registering unit issimilar to the first registering unit which Was used to store thethousands digit and accordingly need not be further described.

As soon as the stepbystep switch SS reaches its fourth position, relaySer will be energized over make contacts Sdn, Ppi, and brush SS@ andwill be over contacts Sei and Ads. By the time relay Ger releases, andythus again vcloses the operated circuit ior the power magnet DSM atbreak contact Gsi, the units digit will have been marked on thecomparator ACC via the following circuit: Alternating current potentialam, brush ll'b, inake contact Bw, brush BSb, conductor b3, make contactSez, break contact Sii, make contact Sii-a and break contact Hai.

l Hence, the iinder DS will hunt for the third time and by taking carethat the alternating current potentials characterizing the units digitsare diferent from those alternating current voltages characterizing thetens digits, the finder DS will stop the third field oi bank contactswhen Torn-l1 BSc reaches a contact to which a corresponding alternatingcurrent potential (pm m) is connected. At this time, the alternatingcurrent comparator ACC will react for the fourth time stopping finder DSon the required position. Again, by providing suitable connections tothe third field of terminals (diagrammatically indicated by JFa), itwill be possible to store the units digits into a third registering unitDar-Dwz This, again occurring by means of an earth connected to the a,19, 0, Wires via make contacts G85, G55, Gsm

The step-.by-step `switch SS will again make one step, Aand willreachits nith position in which relay Sfr Will be energized over brushSSG, and make contact Sdz. Relay Sfr will then be held energized overmake Contact Sfr, winding o relay Sg'r and make contact Ads. Relay Sgrwill later be operated via this holding circuit.

As soon as relay Sfr operates, it will interrupt the previouslyestablished marked circuit to the comparator ACC at make contact Sfi,and it will also short-circuit .relay P101 via make contacts Sfs andAds.

In this Way, it Will be seen that ground potential is temporarilyapplied to the metering conductor from the identification common circuitICC and via make contacts Ada and Sie, break contact Sgr of relay Sgr(which is not yet operated 'but will operate soon after Sfr upon therelease of Ppr), make Contact S415, make or break contact Oes to brushesBSc and IFC or to brushes BSd and IFe.

This ground reaches the master false call circuit MFC, Which requestedthe identication, via first line finder circuit ILF, second line iindercircuit IILF, circuit of nder 'MF and make contact D3. The junctionpoint oi the rectifier Re and resistor r3 being noW temporarilyconnected to ground in the identication common circuit ICC, current willnow be able to ilovv from the source of positive potential +V to groundvia rectifier R2 and relay Sir which vwill be ternporarily energised.Also relay Ar will release because of the ground applied to the circuitSSI. The temporary energization or" relay Sir in the master false callcircuit'MFC Will interrupt the holding circuit for relay Dr, at makecontact Sii whereby this relay will release. On the other hand, relay Erwill remain held over con tact E1 and a contact ofthe key l. When relaySgr operates, following the release oi relay Ppi', ground will no longerbe appliedto the metering vire and accordingly, relay Sir in the masterfalse call circuit MFC will release, but this will not affect relay Drwhich remains in the unoper ated conditionssince relay vEr is stillenergized.

The release of relay Ppr when it is shortcircuited will cause thesubsequent release of relay Pqr at break contact P102, but relay Adrwill not release, being now held over make contact .Sg/2, Abreak contactH12 and make contact Adi.

The de-energization of relay D2' in the master false icall circuit MFCWill now Ypeririit the finder DS -to be connected to the master falsecall circuit MFC by means oi by-path conductors. '32o this eiect, thealternating current potential Which which is characteristic for theparticular identification common circuit ECC is now applied to themarking'side of the comparator ACC via make contact Sfz. On the otherhand, in the same manner as what Was done to obtain access` to :asuitable identification finder IF, this characteristic alternatingcurrent potential will also be used as test potential. occurs 'via thefollowingcircuit: make contact Sii, break contact Hai, make contacts Sdiand Sgi, make contact and make vor break contact Cea to break Contact D3(MFC) via the circuit oi the identification finder IF andthe meteringWire, conductor e4, a contact inthe e bank oi finder DS, brush BSc ofthis finder when it reaches said contact and break contact Has. As inthe previous cases, the circuit for the power magnet aiectthestep-by-step switch SS since the con-- tact Sys is now open. The nderDS having now been `set on the bybreak contact D4, conductor C4, brushDSc,'ccn ductor c2, make contact S94, Winding of relay Hlr and either ofmake contacts L02 or Diz. In

'Dir is energized over make contact Zma or Zm4 asimilar circuitincluding make contacts Dz1 and Ade.

It will be appreciated that n the system described above, contrary toprevious arrangements in which the signalling ofthe calling subscribersminiber` had to take place by means of voice frequency signals via themetering Wire, it is now possible, inthe case oi a local identification,to send the number of the calling subscriber by means of D. C. impulses,directly to the number This has the advantage that the circuit whichrequested an identification, e. g. the masterfalse call circuit MFC,does not need to comprise a voice frequency receiver nor direct currentimpulse repeatingrelays.

Allthe digital information concerning the calling subscribers numberbeing now stored in the contact H21) and will send direct currentimpulses characterizing the calling subscribers line number via makecontacts Los L04, break contacts Dia, D111, brushes DSU; and DSb andconductors a4 and received at the stepping magnet STM. Contacts Aas,Abs, Ac: and Oez have been shown to indicate in a schematic manner thatthe impulse sender IS uses the information derived from the electricalcondition of relays Aar, Abr, Acr, Oer, i. e. hundreds digit.

Neither the impulse sender IS nor the number indicator NI have beenshown in detail since they It should be noted that if the request forthe identification was received from a distant excuit ICC to the circuitwhich requested the identii'lcation.

It is to be noted that when relay Zmr energizes after switch DS has beenset on the Icy-path cirmagnet IFM being closed over oir-normal contactIFON1 and break contact A111.

When the number of the calling subscriber has been obtained on thenumber indicator NI, the release ofthe identification common circuit ICCeration of the auxiliary relay Hmr via make contact H25, whereby sincerelay Hm? will release after relay I-Ilr, the original holding circuitfor relay Adr will be momentarily opened at contact Hm@ causing therelease of relay Adr.

When relay Adr releases, relays Sdi', Ser, Sfr, Sgr Will all releasesince their holding circuit is -for the power magnet DSM of finder nowinterrupted at contact Ada. The release of' relay Sgr will cause therelease of relay Zmr (at contact Sgt) whereby a circuit will now beclosed DS via break Contact Zmi, ofi-normal' contact DSON2 and breakcontact Adg. In this manner, finder DS will be returned to the normalposition. Also, when relay Adi` is released, step-by-step switch SS willbe returned to the home position (break contact Adm and ofi-normalcontact SSON1) Relays Aar, Abr, Aer, Oer, L01 or Dir will also release(contacts Adi, Adz and Adg) and the identification common circuit ICCwill thus be brought back to its normal condition.

It has been mentioned above that characteristic signals will have to beprovided to the identification common circuit ICC depending whether theidentification is requested from a local circuit or from a circuitlocated at a distant exchange, e. g. ground on the d wire leading tobrush DSa. or ground o n the b wire leading to brush DSBbi. In a similarmanner, other characteristic signals can also be sent to theidentification common circuit causing the latter to vary the number ofdigits of the subscribers number which have to be signalled to thecircuit requesting the identification. In the above mentioned embodimentwhich was described in detail, it was assumed that the identificationwas requested by a local circuit in which case it is only necessary tosignal the local subsoribers number. If a request foridentification'cornes from a circuit which can only be reached over ajunction, the finder DS will, in this case, be set on a selector FSi (e.g. Fig. 1) corresponding to a group of junctions from another networkand this will be notied to the identification common circuit ICC by theprovision of a third characteristic signal e. g. a simultaneous groundon the u and b conductors whereby, by means not shown but obvious tothose skilled -in the art, the identification common circuit will thencause the local subscribers number to be signalled to the circuitrequesting identification but preceded by the digits or" the localprefix.

Advantages of the use of direct current potential for identifying thecalling line The use of a direct current potential for marking thecalling line to be identified results in the following advantages:

I. If, during the course of the different functions performed by theidentification circuits, a disturbance occurs, the identificationcircuit in some cases may break down the identification and then switchitself oi. t positive potential is removed from the metering wire in thecircuit requesting identification, the potential on this metering wireis restored to its first value by the release of the identificationcircuit which disconnects the holding relay Ppr from the metering wire,so that the starting circuit for the identification again operates andthe identification process commences again. This feature of theinvention is made possible by using a direct currentl potential both asstarting potential and test potential for the identification circuits.When using direct current potentials, known means, such as polarizedrectifiers, are used to obtain an accurate marginal working, so that areduction of a potential already of small value may be positivelyrecognized and may be used for initiating the operation of the startingcircuit. In the circuit arrangements known hitherto, exclusive use wasmade of alternating current potentials for marking the calling linewhile If this happens before the the starting signal for theidentification was given, this starting signal being given from thecircuit which requested identification in addition to the marking signaland independent thereof. rihe starting signal could be disconnected bytransmitting an alternating current signal from the identificationcircuit to the circuit requesting identification. After thisdisconnection-signal was once transmitted, however, the startingpotential was broken and could not be closed again under the control ofthe identification circuit, e. g. in case of the disturbance asmentioned above.

Il. The use of a direct current potential makes it possible also to holdthe identification circuit under the control of the circuit requestingidentication and under all conditions, so that if, for any reasonwhatsoever, the identification process were to be stopped or were tohave to start again, it would be possible to release the identificationcircuit in all these above mentioned cases by simply interrupting thepositive potential in this circuit requesting identification.

In this manner it is possible, for example, to release theidentification circuit at any moment, as a result of a premature releaseof the call, or if, for example, a toll traffic operator wishes to havethe identification restarted because a first effort in this directionhad no success because of some faults in the equipment.

In the arrangements hitherto known wherein alternating current was usedfor marking the calling line, this was not possible.

III. The use of a direct current circuit for the identication makes itfurther possible to use this circuit at a later moment to connect up aby-path, so that the signalling of the number of the calling subscribercan take place along this by-path, as described above.

Advantages of 1. A characteristic alternating current potential issimultaneously connected to all finders IF r vof a group, but only whenan identification circuit ICC-wishes to select an idle circuit of thisgroup by the selector switch BS.

2.' This potential is different for each identification circuit, so thatvarious of these circuits may simultaneously control the setting oftheir switch BS without mutual interference, because each switch BS canbe independently stopped on a terminal at which a particular alternatingcurrent potential is present, being characteristic for the associatedidentification circuit ICC.

3. The identification circuit only connects the alternating currentpotential to one group of finders IF, and this group is determined bymeans of the starting circuit which was seized by the identificationcircuit and which serves the same groupof 200 subscribers as the wantedgroup of finders IF. If viz. the alternating current potential isconnected finder CC, this potential will be connected with the startingcircuit initiating the identification process, as above mentioned, astarting circuit is connected to the line finders of the same two groupsof subscribers which are served by a group of identification finders IF,so that the starting circuit when extending the alternating currentpotential to the corresponding` group of identification finders, causesthis potential to be connected to the test conductor of the finders,serving the group of 200 subscribers, in which the calling line isconnected.

via wiper CCC of 2,686,840 Advanys f the method used for holding theThis description will be made llxvithreference to identification commoncircuit Figs. 1 to 3. l As :has been set out above, the holding of theA' IDENTIFICATION VIA A SINGLE JUNCTION identification circuit `ICCtakes place `under the 5 The principles for the denticato of callingsubscribers which are connected in different exchanges is known and havebeen described for the `starting circuitls broken and the holding ofaccordance with th y the identification circuit ICC takes place under besummarized as fllsem Invention they may a. A circuit re uestinidentification in an exeratesvia the metering wire fromthe circuit re-Change (pi, mqbeing gdistant `fmn that with questiilg dnt1f- 3a171011-15 which the calling subscriber is connected (Fig.

Durme the tlm@ that the Ender IF is bulli/111g l), connects a positivepotential to the so-called fQ he Calllng 1111, the ldlltlatwn CHSUI ICCincteiine whe, which in the incoming selector,

ensured, at any moment Only one 0f the a Small rectifier Rl' isconnected to a com.. onderen of o group een hunt for aeallng-Uemonpoint, leading to a starting circuit SC The? thlss Indeed oorl'eet ispoVed from the for identification via junctions. Furthermore,consideratlon that a Starting Circuit has been this metering Wire" isalso connected in the terprovided in Common fofthe line ndesof thosemina] arcs of one or more `:lnder circuits IFz two groups of hundredlneewhich may be Served for identification via junctions. In case of an b yone group of loentlooetoo ondelfs 1F: and: identification call, thestarting circuit hunts for smc@ only one starting elromt 1S profldedCorre" an idle connecting circuit for identication Via Spondng t0 eachgroup 0f ndel's IF', and Smc@ junctions (Doo). This circuit mainiybymeans this starting circuit can only hold one identicaof its Selector Bsestablfles a Connection tion circuit at a time, thislast `mentionedcircuit to an idle finder onfout TF2 n *d grond giving can Cause onlyone onder IF to Performa hunt* access to the incoming `junction. `Theidening movement at e time BY this arrangement tity ofthe originatingexchange and also the two or more Enders `IF cannot simultaneouslynumber of the junction are determined by the test the metering wireofthe `subscribers line group of une finders H32 ELnd the position inCircuit 35 which one of these iinders will be set res i y DGC- If, thslast Tesult had not been obtemed o tively, wherein each direction ofincoming juncdouble test device would have to be provided, tions isassoojatod with d group of ndors which would operate in` known mannerafter the o By moans of its dndol. CS the identioa;

tenders had stopped Simultaneously on the Calling tion connectingcircuit now `obtains access lto an line, which said device, inadditionto two extra 4o idle juno/don 0G52 leading to ,the Originating nder IFwould requne a test Wlre pel' Sub" of the ordinary Junctions serving thesubscribers scribers line, the costs of which would be extramo in adlrootlon opposlte to that of the can tremely high for uns purpose i forwhich the calling subscriber has to be iden- It Wm be oleel toot eeSoones relay hes tied. This outgoing junction maybe directlytakenovelthe homme 0f the ldentlatlon C11" accessible in `the arc of theunder cs or it may cuit `and this has broken the operation of the bereached Via an extra Selector tage (not starting circuit for the groupunder considera- 5hoWn) bel-ng connected inthe aros ofc This non thisstarting Circuit may immediately be extra `selector stage also consistsof ordinary operatedior another case of identification inthis solectordwhich are usedlfm. Subscribe trame Same group of 200 subsofbefs linesWith the in a direction, opposite `to that of the call to result, that asecond nder XF starts to perform beidened l ahunting action `While thefirst one in connec- ,c The identca tion with the first group `is stillbeing heid. l caro that This second finder cannot be stopped, however,on the first considered subscribers line,

since the positive potential at the metering Wire thereof 15.5 reduite`to. ,the testmdeme 1.o the exchange, @which the cant-ope identified the1dent1iicat1on circuit which conti 01s each` belonged This happems inknown manner settmg 0I IF canpot respond to 1t" Tneause oo whereafterthe foilowingicocles are `sent to this register: i i

l. A first code represents thevnumber "11 and gives the indicationto theincoming registerthat it has to deal `with arca-se ofidcntiiicatiori.The incoming register then sets the incoming selector INCGS to a groupselector `in a group, `which is specialy provided for identification,Via `junc- The provision of a ooicefrcquency signal chanone I-Gsl ano-Whloh may be ree'ohed We' fe nel as bi1-path, forthe epeechchanncl`through, separate terminal row of the incoming selector,

on connecting circuit takes after access has been obtained 5to theincluded inthe static switch'areonly conductive 65 tmdem exchange whichrow, however, is not used forthe regular subscribers traiiic. Inrorderto explain a case of a tandem con- Subsequently WO digits are Sent t0indicate nection, a description will rst be given of the the junctlongroup of which useis made on behalf ing exchange'causes a selection totake place of a final selector for identification via junctions FSi,wherein a group of these finder selectors is arranged in co-operationwith each junction group. This final selector is reached by either oneor two selections and is then either directly connected in the arcs ofthe identification group selectors II.GS1, as set out above, or in thearcs /of a second stage of similar group selectors IILGSL This last factdepends upon the number of directions to be reached and also upon thetotal number of junctions leaving the exchange, which conditionstogether determine whether all final selectors can be reached via oneselector stage or via two required selector stages.

3. Finally two codes are sent which correspond to the position of theidentification nder IFZ (Fig. 2) and which therefore indicate the numberof the junction which was used for the call to be identified. Under thecontrol of these two digits the final selector FSl is set to theoutgoing end of this junction.

d. When the above-mentioned has been completed, it is clear that a newcircuit has now been established from the incoming end of the junctiondealing with the call to be identified to the outgoing end thereof,wherein this by-path from the incoming end of the junction may befollowed, via a finder circuit IFz and the selector BS of theidentification connecting circuit DCC, and subsequently, via finder CSof this connecting circuit, either directly, or via a second groupselector (not shown), to the outgoing end of a two-wire junction in theopposite direction, and from there, via this junction and the incomingselector INC.GS at the originating exchange, and via one or two stagesof group selectors to the final selector FSl for identification, whichis set to terminals corresponding to the outgoing end of the junction tobe identified.

e. As soon as the outgoing end of the junction, which is used for thecall to be identified, has been reached, a positive potential is appliedto the metering wire leading to this outgoing junction circuit. Thispositive potential is supplied from the incoming register (Fig. 1) whichis still connected, with the result that the identification starts atthe originating exchange in the abovementioned general way, i. e. thispositive potential will actuate the starting circuit SC' (Fig. 1).

f. As soon as the identification circuit ICC (Fig. l), which was seizedfor identifying the calling subscribers line at the originatingexchange, has performed its function up to the point where it has set afinder IF to the terminal of the calling line and has determined thenumber of the calling line, this circuit will set its switch DS in theafore-described manner to the circuit requesting identification. In thepresent case the circuit requesting identification is the final selectorFS1 and this circuit is connected in the arcs of switch DS of theidentification circuits. lSwitch DS is therefore set to these terminalsand subsequently establishes a direct connection between theident'fication circuit ICC and the final selector FSi. The direct groundsupplied to the metering wire in order to effect the switching-over ofthe positive potential, is now transferred to the incoming register(Fig. 1) which upon reception thereof, disconnects itself.

'g. The fact that switch DS (Fig. 1) has set itself to the finalselector for identification via junctions causes a signal to be sent tothe identification circuit 1n order to notify it of the fact leading tothe tandem exchange.

- potential on to the that it hasV to deal with a case of distantidentification. Subsequently itwill send out the numerical digits of thecalling subscribers line in the form of voice frequency impulses via the"a and bf wipers of switch DS, namely in a` manner as has been alreadydescribed above. These voice frequency signals are now passed throughthe final selector different group selectors through which the finalselector is connected to the incoming junction, which is seized onbehalf of the identification, as well as through this junction itself,viawhich the voice frequency signals are now transmittedv to the distantexchange (Fig. 2). At this exchange they are passed e'ther directly orvia an intermediate group selector to the connecting circuit foridentification DCC where they are received by a voice frequency signalreceiver converting the signals in question into direct currentimpulses. h. Meanwhile, the connecting circuit for identication DCC hasbuilt up a by-path by means of a switch DS to the circuit requestingidentification in a manner which is completely identical to thatoutlined above for the case of the identification circuit ICC. Thealternating current impulses received in the connecting circuit DCC aretherefore converted into direct current impulses and are directlytransmitted from this connecting circuit, via switch DS to the circuitrequesting identification.

B. IDENTIFICATION VIA MORE THAN ONE JUNC- TIoN IN TANDEM The case shouldnot be considered that a call was made from the originating exchange(Fig. 1), via a tandem exchange (Fig. 2), to a subscriber which isconnected to the terminal exchange (Fig. 3). In this case theidentification takes place as follows:

(a) Identification starts by the intermediance of a circuit which at thefinal exchange (Fig. 3) requests identification and, in the mannerabovedescribed, the connection is established from a connecting circuitfor identification DCC (Fig..3) to the incoming junction INC.GS" whichterminates at the terminating exchange. In the abovedescribed mannerthis connecting circuit determines the group of junctions as well as thenumber of the incoming junction at the terminating exchange, which wasseized for the call to be identied, and then starts by lseizing ajunction At this tandem exchange an incoming register INCGS (Fig. 2) isseized and by means of codes, received from the connecting circuit DCCat the terminal exchange (Fig. 3), a by-path is then set to the outgoingend of the junction OGJ3 between the tandem exchange and the terminatingexchange,

concerned with this call.

(b) As soon as the incoming register and the tandem exchange hasobtained access to the outgoing end of the junction leading to theterminating exchange, this register applies a positive metering wireleading to this outgoing end in the above-described manner, whilefurthermore this positive potential is now transmitted to the incomingend of the junction from the originating exchange to the tandem exchangewhich Was seized for the call to be identied. In consequence of thisfact, at the tandem exchange (Fig. 2) a connecting circuit foridentification DCC is connected to this incoming junction, the workingof this connecting circuit being similar to that illustrated above, sothat now. under the control thereof, a by-path will be es- FS1 andthrough the Y terminating exchange.

25 tablished, via a two Wire junction leading to the `and from, theretothe outthis has happened, the identification starts at the originatingexchange in the described manner.` i

(c) Meanwhile the connecting circuit for identication' at the tandemexchange (Fig. 2)Will now build up a by-Dath by means of its switch DSto the circuit requesting identification, which circuit in this case isthe nal selector FSi' (Fig.

2) which was seized at the tandem exchange. In

this manner this connectingcircuit establishes a signal channeljunctions from the originatlng exchange to the This signal channelextends from selector Fiat' the originating exchange (Fig. 1) throughonel or two selectors II.GS1 and III.GS1, the incoming selector IN C GS,and subsequently, via the junction seizedfor iden` tication purposesfrom the originating exchange to the tandem exchange, selector CS of theidento the circuit which requested identification, e.v g. FIM (Fig. B) i(d) As soon as' the identificationcircuit at the originating exchangehas completed thewidentication of the the originating exchange to thetandem exchange and via the signal channel at the tandem e change, asmentioned under c, to thejunction which was temporarily seized foridenticationwhere, inl the manner as delz (Identificationvia extended tothe con-l fluency` impulsesY received' 'from the originating directlysent to the terminating exchange. t t u (e) It maybe noted that theconnecting circuit for identification at the tandem` ex:- change` isused in the condition in which it directly transmits `thevoiceffrequency impulses via:` Onef junction to another junction as aAresult of the fact that the position of its switch DS vides theindication that the' identification was requested from a distantexchange. The voice frequency receiver Aforming part of thisconnectingcircuit is therefore not connected e'a'ch time connection.`

The invention is `not restricted to' the' abov'e described embodiments.

Instead of using a positive direct current poten# tial as characteristicpotential for identiii'cation a negative direct current potential may beequally respond to a higher potential.

Satisfying this requirement has `proved practi1 cable from differentcircuit arrangements, which have already been applied.`

In addition to the use of an alternating circuit potential withtentials'for of different of diferent value'.

In other parts of the circuit The shown circuit arrangement therefor'does not possessany limitative character.

\ What is claimed:

1I. AnI automatic teleplione'system`-f ir establish-- determined value,means at each request circuit for initiating the request foridentification of` a calllng line connected L saidsource of potentialtothe conductor of said

